It was next considered whether the air did not contribute to the generation of this heat; and our author determined that this could not be the case; because the quantity of heat generated was not sensibly diminished when the free access of air was prevented. From another experiment it appeared that the generation of the heat was neither prevented nor retarded by keeping the apparatus immersed in water. Here the friction generated so much heat, that in one hour the temperature of the water surrounding the cylinder was raised from 60 to 107 degrees of Fahrenheit. In half an hour more it was raised to 142; at the end of two hours to 178; at two hours 20 minutes to 200; and in two hours and a half it boiled.[78] On the whole, Count Rumford concludes, that “the quantity of heat, produced equably by the friction of the blunt borer against the bottom of the hollow metallic cylinder, was _greater_ than that produced equably in the combustion of _nine wax candles_, each three quarters of an inch diameter, all burning at the same time with a clear, bright flame.” From all these experiments, however, our author does not draw any certain conclusion. “What is heat? (says he.) Is there any such thing as an _igneous fluid_? Is there any thing that can with propriety be called _caloric_? The heat produced, in the author’s experiments, by the friction of two metallic surfaces, was not furnished by small particles of metal, detached from the larger solid on their being rubbed together. It was not supplied by the air, because the machinery in three experiments was kept under water, and the access of atmospherical air completely prevented. It was not furnished by the water which surrounded the machinery, because this water was continually receiving heat from the machinery and could not at the same time be giving to and receiving heat from the same body; and because there was no chemical decomposition of any part of this water.” At last he observes, that the source of this heat, whatever it is, must evidently be inexhaustible, adding, that “any thing, which any _insulated_ body, or system of bodies, can continue to furnish _without limitation_, cannot possibly be a _material substance_; and it appears to me to be extremely difficult, if not quite impossible, to form any distinct idea of any thing capable of being excited and communicated, in the manner the heat was excited and communicated in these experiments, except it be MOTION.” [78] The quantity was two gallons and a quart, wine measure.